JPH1162644A - Valve actuation timing control device for internal combustion engine of compression auto-ignition type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a torque drop resulting from a too early auto-ignition, generation of colliding sounds of a piston with connecting rod, and also prevent misfire caused by shortage of the duration of compression stroke. SOLUTION: In case the engine speed is high or the air-fuel ratio of the mixture gas in a combustion chamber 4 lies on the lean side, a sufficient duration of compression stroke is secured by putting earlier the closing timing of an intake valve 7, and thereby misfiring resulting from shortage of the duration of compression stroke can be prevented. In case the engine speed is low or the air-fuel ratio of the mixture gas in the combustion chamber 4 lies on the rich side, the auto-ignition timing is delayed by putting later the closing timing of the intake valve 7, which allows prevention of a torque drop and generation of colliding sounds of a piston with connecting rod caused by a too early auto- ignition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for a compression ignition internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, compression self-ignition is performed in which the temperature of an air taken into a combustion chamber of an internal combustion engine is increased by compressing the air, and the air is brought into contact with fuel injected into the combustion chamber to ignite and burn. BACKGROUND ART Internal combustion engines are known. Further, in order to improve the startability and combustion noise of an internal combustion engine, a valve operation timing control device for a compression ignition internal combustion engine that controls the valve operation timing of a compression ignition internal combustion engine according to the engine load is known. ing. An example of this type of valve operation timing control device for a compression ignition internal combustion engine is disclosed in Japanese Utility Model Laid-Open Publication No. 61-19606.

[0003]

However, the apparatus described in Japanese Utility Model Laid-Open Publication No. Sho 61-19606 sets the valve operating timing of the compression ignition type internal combustion engine in accordance with the engine speed and the air-fuel ratio in the combustion chamber. Can't control.

Therefore, when the engine speed is high, if the intake valve is closed at the same time regardless of the level of the engine speed,
As compared with the case where the engine speed is low, the time point at which the ascending stroke of the piston ends is earlier, so that the period of the compression stroke becomes shorter. As a result, the temperature of the air in the combustion chamber does not rise sufficiently, causing a misfire.

On the other hand, when the engine speed is low, if the intake valve is closed at the same time regardless of the level of the engine speed, self-ignition will occur before the piston ascent stroke ends. As a result, the force that pushes down the piston due to the combustion of fuel and the force that tries to raise the piston during the ascent stroke cancel each other, the torque decreases, and the sound of the collision between the piston and the connecting rod is reduced. It gets bigger.

Further, when the air-fuel ratio in the combustion chamber is lean, the rate of temperature rise of the air in the combustion chamber per hour due to compression is smaller than when the air-fuel ratio is rich. As a result, if the intake valve is closed at the same time regardless of the air-fuel ratio, the period of the compression stroke will be shorter than when the air-fuel ratio is rich, and the temperature of the air in the combustion chamber will rise sufficiently. Without doing so, they will misfire.

On the other hand, when the air-fuel ratio in the combustion chamber is rich, the rate of temperature rise per hour of the air in the combustion chamber due to compression is greater than when the air-fuel ratio is lean. As a result, if the intake valve is opened at the same time regardless of the magnitude of the air-fuel ratio, the air in the combustion chamber reaches the self-ignition temperature before the end of the piston ascent stroke, and self-ignites. As a result, the force that pushes down the piston due to the combustion of fuel and the force that tries to raise the piston during the ascent stroke cancel each other, the torque decreases, and the sound of the collision between the piston and the connecting rod is reduced. It gets bigger.

In view of the above problems, the present invention prevents a misfire due to a short period of a compression stroke, a decrease in torque due to premature ignition, and a collision noise between a piston and a connecting rod. It is an object of the present invention to provide a valve operation timing control device of a compression ignition type internal combustion engine which can be operated.

[0009]

According to the first aspect of the present invention, in a valve operation timing control apparatus for a compression ignition type internal combustion engine having an intake valve, the intake valve closes as the engine speed increases. A valve operation timing control device for a compression ignition internal combustion engine, wherein the valve timing is advanced is provided.

According to the first aspect of the present invention, when the engine speed is high, the valve closing timing of the intake valve is advanced to ensure a sufficient compression stroke period when the engine speed is high. Therefore, it is possible to prevent a misfire due to a short period of the compression stroke. On the other hand, when the engine speed is low, the self-ignition timing is delayed by delaying the closing timing of the intake valve, and therefore, a decrease in torque due to too early self-ignition and the generation of a collision sound between the piston and the connecting rod are caused. Can be prevented.

According to a second aspect of the present invention, in the valve operation timing control apparatus for a compression ignition type internal combustion engine having a combustion chamber and an intake valve, the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber is controlled. A valve operation timing control apparatus for a compression ignition internal combustion engine is characterized in that the closing timing of the intake valve is advanced as the leaner.

According to the second aspect of the present invention, when the air-fuel ratio is lean, the valve closing timing of the intake valve is advanced to secure a sufficient period of the compression stroke. Therefore, it is possible to prevent a misfire due to a short period of the compression stroke. On the other hand, when the air-fuel ratio is rich, the self-ignition timing is delayed by delaying the closing timing of the intake valve, and therefore, the torque is reduced due to the self-ignition prematurely, and the collision noise between the piston and the connecting rod is generated. Can be prevented.

According to a third aspect of the present invention, there is provided a throttle valve and a throttle valve opening changing means for changing an opening of the throttle valve, wherein the throttle valve opening changing means is configured to control an engine speed. The valve operating timing control device for a compression ignition type internal combustion engine according to claim 1 or 2, wherein the opening degree of the throttle valve is increased when the rate of change is positive.

According to a third aspect of the present invention, there is provided a valve timing control apparatus for a compression ignition type internal combustion engine, the response delay of the valve timing control being controlled when the rate of change of the engine speed during the engine transient operation is positive. Despite the occurrence and the shortage of the substantial compression stroke, the pressure of the air-fuel mixture at the time of closing the intake valve can be increased by increasing the throttle opening, and therefore, In the compression stroke, the air-fuel mixture can be compressed as much as necessary and self-ignited at an appropriate time.

According to a fourth aspect of the present invention, there is provided a throttle valve and a throttle valve opening changing means for changing the opening of the throttle valve. The valve operating timing control device for a compression ignition type internal combustion engine according to claim 1 or 2, wherein the opening degree of the throttle valve is reduced when the rate of change is negative.

According to a fourth aspect of the present invention, there is provided a valve timing control apparatus for a compression ignition type internal combustion engine, wherein a response delay of the valve timing control is reduced when the rate of change of the engine speed during the engine transient operation is negative. Despite the occurrence and the substantial period of the compression stroke being excessive, the pressure of the air-fuel mixture at the time of closing the intake valve can be reduced by reducing the throttle opening, and therefore, In the compression stroke, the air-fuel mixture can be compressed as much as necessary and self-ignited at an appropriate time.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a first embodiment of a valve operation timing control device for a compression ignition type internal combustion engine according to the present invention. In FIG. 1, reference numeral 1 denotes a piston that reciprocates up and down in a cylinder, 2 denotes a crankshaft that rotates according to the movement of the piston 1, and 3 denotes a connecting rod that connects the piston 1 and the crankshaft 2. Reference numeral 4 denotes a combustion chamber for burning the air-fuel mixture, 5 denotes an intake port, and 6 denotes an exhaust port. 7 is an intake valve provided in the intake port 5, 8
Is an exhaust valve provided in the exhaust port 6. Reference numeral 9 denotes an intake camshaft provided with an intake cam (not shown) for driving the intake valve 7, and reference numeral 10 denotes an exhaust camshaft provided with an exhaust cam (not shown) for driving the exhaust valve 8. 1
1 is an intake cam pulley attached to the intake camshaft 9, 12 is an exhaust cam pulley attached to the exhaust camshaft 10, and 13 is a crankshaft pulley attached to the crankshaft 2. Reference numeral 14 denotes a timing belt or a chain for transmitting the rotational driving force of the crankshaft 2 to the intake camshaft 9 and the exhaust camshaft 10. Reference numeral 15 denotes a known VVT (variable valve timing device) provided between the intake camshaft 9 and the intake cam pulley 11 for changing the operation timing of the intake valve 7.
It is. Reference numeral 16 denotes an injector provided in the intake port 5, and reference numeral 17 denotes a throttle valve for adjusting an intake air amount. Reference numeral 18 denotes intake valve closing timing detecting means such as a cam angle sensor for detecting the closing timing of the intake valve 7. 19 is an air-fuel ratio sensor provided in the exhaust port 6,
Reference numeral 20 denotes an engine speed sensor, and reference numeral 21 denotes an accelerator opening sensor. Reference numeral 22 denotes a throttle valve driving unit (not shown) for driving the VVT 15, the injector 16, and the throttle valve 17, an intake valve closing timing detecting unit 18, and the air-fuel ratio sensor 1.
9, an ECU electrically connected to the engine speed sensor 20 and the accelerator opening sensor 21.

As shown in FIG. 1, first, in the downward stroke of the piston 1 when the intake valve 7 is opened, that is, in the intake stroke,
A mixture of air and fuel is sucked into the combustion chamber 4 through the intake port 5. Subsequently, in the rising stroke of the piston 1 after the intake valve 7 is closed, that is, in the compression stroke, the temperature of the air-fuel mixture rises, and the heated air-fuel mixture self-ignites and explodes.

FIG. 2 is a flow chart showing a valve operating timing control method according to this embodiment. As shown in FIG. 1 and FIG. 2, when the valve operation timing control starts, first, in step 101,
, The intake valve closing timing detecting means 18 detects the intake valve 7
Read the actual valve closing timing of. Subsequently, in step 102, the engine speed is read by the engine speed sensor 20. Subsequently, in step 103, the air-fuel ratio of the air-fuel mixture in the combustion chamber 4 calculated based on the air-fuel ratio of the exhaust gas detected by the air-fuel ratio sensor 19 provided in the exhaust port 6 is read. Subsequently, at step 104, the read engine speed, the air-fuel ratio of the air-fuel mixture, and the ECU
The target valve closing timing is calculated from the map values shown in FIG. FIG. 3 is a map showing the relationship between the engine speed, the air-fuel ratio of the air-fuel mixture, and the target closing timing of the intake valve. As shown in FIG. 3, the target valve closing timing of the intake valve is advanced as the engine speed increases, and is advanced as the air-fuel ratio of the air-fuel mixture becomes lean.

Returning to FIG. 2, in step 105, it is determined whether or not the actual closing timing of the intake valve 7 is earlier than the target closing timing. When the determination is Yes, in step 106, the closing timing of the intake valve 7 is delayed by the VVT 15, and then the process proceeds to step 109. on the other hand,
If No, it is determined in step 107 whether the actual closing timing of the intake valve 7 is later than the target closing timing. If the determination is Yes, step 10
At 8, the valve closing timing of the intake valve 7 is advanced by the VVT 15, and then the routine proceeds to step 109. On the other hand, if No is determined, the process directly proceeds to step 109.
In step 109, it is determined whether or not to terminate the valve operation timing control.
It is determined as s, and the valve operation timing control ends. On the other hand, when the valve operation timing control is to be continued, No is determined, and the above-described steps are repeated.

When the engine speed is high, the target valve closing timing earlier than the actual valve closing timing is calculated in step 104, and the valve closing timing of the intake valve is advanced in step 108 when the engine speed is high. be able to. As a result, the period of the compression stroke can be sufficiently ensured even though the time of reaching the top dead center is early, so that misfire due to the shortage of the period of the compression stroke can be prevented.

On the other hand, when the engine speed is low, the target closing timing later than the actual closing timing is calculated in step 104, and the closing timing of the intake valve can be delayed in step 106. As a result, the start time of the temperature rise of the air-fuel mixture can be delayed, and therefore, the self-ignition timing can be delayed until reaching the top dead center. Therefore, it is possible to prevent a decrease in torque due to too early self-ignition and a generation of a collision sound between the piston and the connecting rod.

Further, when the air-fuel ratio of the air-fuel mixture is lean, a target closing timing earlier than the actual closing timing is calculated in step 104, and the closing timing of the intake valve can be advanced in step 108. As a result, it is possible to secure a period of the compression stroke sufficient to raise the temperature of the air-fuel mixture having a low temperature rise rate to the self-ignition temperature, and therefore, it is possible to prevent a misfire due to a shortage of the period of the compression stroke. it can.

On the other hand, when the air-fuel ratio is rich, the target closing timing later than the actual closing timing is calculated in step 104, and the closing timing of the intake valve can be delayed in step 106. As a result, the temperature rise start time of the air-fuel mixture can be delayed. Therefore, the self-ignition timing can be delayed until reaching the top dead center even though the temperature rise rate of the air-fuel mixture is high. therefore,
It is possible to prevent a decrease in torque due to premature ignition of self-ignition and a generation of a collision sound between the piston and the connecting rod.

When the valve of the compression ignition type internal combustion engine of the present invention is operated
In the second embodiment of the phase control device,
The valve operation timing control during engine transient operation
Throttle opening to compensate for response delays in valve timing control
The degree change control is performed. FIG. 4 shows the throttle according to the present embodiment.
It is a flowchart which shows an opening degree change control method. Figure 1 and
As shown in FIG. 4, the throttle opening change control starts.
Then, first in step 201, the engine speed
At the first time by the sensor 20 and the accelerator opening sensor 21.
Interval t₁Engine speed Ne₁(T₁) And acces
Opening degree B₁(T ₁) And read. Then step 20
In 2, the second time after a lapse of a predetermined time from the first time
Interval t_TwoEngine speed Ne_Two(T_Two) And acces
Opening degree B _Two(T_Two) And read. Then step 20
3, the engine speed Ne ₁(T₁) And Ne_Two
(T_Two) To the difference ΔNe (= Ne) in the engine speed.
_Two(T _Two) -Ne₁(T₁)). Then
In step 204, the accelerator opening B₁(T₁) And B
_Two(T_Two) To the difference ΔB (= B
_Two(T_Two) -B₁(T₁)).

In step 205, it is determined whether the absolute value | ΔNe | of the difference between the engine speeds is larger than a predetermined value A. In the case of Yes, it is determined that the response delay of the valve operation timing control occurs during the engine transient operation and the process proceeds to step 206. In the case of No, it is determined that the response delay of the valve operation timing control does not occur, and the process proceeds to step 213. In step 206, it is determined whether or not the value of the difference ΔNe between the engine speeds is positive. If Yes, it is determined that the engine is accelerating, and the process proceeds to step 207. If No, it is determined that the engine is being decelerated and step 210 is executed.
Move to

In step 207, R
The correction coefficient α is read from the map value shown in FIG. 5 stored in the OM. FIG. 5 is a map showing the relationship between the time and the correction coefficients α and β. As shown in FIG.
Is a positive value and decreases with the passage of time from the start of the throttle opening change control. The correction coefficient β is a negative value, and increases with the passage of time from the start of the throttle opening change control. Subsequently, in step 208, the throttle opening change control amount ΔT (= α × | ΔB | ×) is obtained from the absolute value | ΔB | of the difference between the correction coefficient α and the accelerator opening and the absolute value | ΔNe | of the difference between the engine speeds. | ΔNe |) is calculated. Subsequently, in step 209, step 20
Based on the positive throttle opening change control amount ΔT calculated in step 8, the throttle valve 17 is driven to change the throttle opening, that is, the throttle opening is increased, and the routine proceeds to step 213.

On the other hand, in step 210, the ECU
The correction coefficient β is read from the map value shown in FIG. Subsequently, in step 211, the absolute value | ΔB of the difference between the correction coefficient β and the accelerator opening degree
And the absolute value | ΔNe | of the difference between the engine speeds and the throttle opening change control amount ΔT (= β × | ΔB | × | ΔN
e |) is calculated. Subsequently, in step 212, the throttle valve 17 is driven to change the throttle opening based on the negative throttle opening change control amount ΔT calculated in step 211, that is, the throttle opening is decreased, and step 213 is performed. Move to

In step 213, it is determined whether or not to terminate the throttle opening change control. For example, when stopping the engine, the determination is Yes and the throttle opening change control is terminated. On the other hand, when the throttle opening change control is to be continued, No is determined, and the above-described steps are repeated.

In FIGS. 1, 2 and 4, in the valve operation timing control of the first embodiment described above, when the value of the difference ΔNe of the engine speed during the engine transient operation is positive,
That is, when the rate of change of the engine speed is positive, the engine speed changes between when the actual valve closing timing is read in step 101 and when the valve closing timing is advanced in step 108. Therefore, a response delay of the valve operation timing control occurs, that is, the valve closing timing cannot be advanced as much as necessary. As a result, the period of the substantial compression stroke becomes insufficient. In the throttle opening change control of the second embodiment described above, in that case, step 2
At 09, the throttle opening change control is performed to increase the throttle opening. As a result, the pressure of the air-fuel mixture in the combustion chamber 4 when the intake valve 7 is closed can be increased. Therefore, the air-fuel mixture is compressed as much as necessary in the compression stroke, and self-ignition is performed at an appropriate time. be able to.
As described above, since the correction coefficient α decreases with the passage of time, the throttle opening change control amount becomes zero after a lapse of time as long as the response delay of the valve operation timing control is eliminated.

On the other hand, in the above-described valve operation timing control of the first embodiment, when the value of the engine speed difference ΔNe during engine transient operation is negative, that is, when the rate of change of the engine speed is negative The engine speed changes between when the actual valve closing timing is read in step 101 and when the valve closing timing is delayed in step 106. Therefore, a response delay of the valve operation timing control occurs,
That is, the valve closing time cannot be delayed as much as actually required. As a result, the period of the substantial compression stroke becomes excessive. In the throttle opening change control of the second embodiment described above, in that case, the throttle opening change control is performed in step 212 to reduce the throttle opening. As a result, the pressure of the air-fuel mixture in the combustion chamber 4 at the time of closing the intake valve 7 can be reduced. Therefore, the air-fuel mixture is compressed as much as necessary in the compression stroke, and self-ignition is performed at an appropriate time. be able to. As described above, since the correction coefficient β increases with the passage of time, the throttle opening change control amount becomes zero after a lapse of time that eliminates the response delay of the valve operation timing control.

In the above-described embodiment, whether or not the engine is in the transient operation is determined by using the engine speed sensor 20, but in other embodiments, it is determined whether or not the transmission has been shifted. It is also possible to make a determination using a detection means (not shown). Further, in the embodiment shown in FIG. 1, the injector 16 is provided in the intake port 5, but in another embodiment, as shown in FIG. 6, the injector 16 'may be provided in the combustion chamber 4. is there.

[0034]

According to the first aspect of the present invention, it is possible to prevent a misfire due to a short period of the compression stroke when the engine speed is high, and to prevent self-ignition when the engine speed is low. It is possible to prevent a decrease in torque due to premature ignition and a generation of a collision sound between the piston and the connecting rod.

According to the second aspect of the present invention, when the air-fuel ratio is lean, it is possible to prevent misfire due to the shortage of the compression stroke period, and when the air-fuel ratio is rich, it is possible to prevent self-ignition. It is possible to prevent a decrease in torque due to premature ignition and a generation of a collision sound between the piston and the connecting rod.

According to the third aspect of the present invention, when the rate of change of the engine speed during the transient operation of the engine is positive, a response delay of the valve operation timing control occurs, and the substantial compression stroke is reduced. Despite the shortage of the period, the pressure of the air-fuel mixture at the time of closing the intake valve can be increased, so that the air-fuel mixture is compressed as much as necessary and sufficient in the compression stroke, and automatically at an appropriate time. Can be ignited.

According to the fourth aspect of the present invention, when the rate of change of the engine speed during the transient operation of the engine is negative, a response delay of the valve operation timing control occurs, and the substantial compression stroke is reduced. Despite the excessive period, the pressure of the air-fuel mixture at the time of closing the intake valve can be reduced, and therefore,
In the compression stroke, the air-fuel mixture can be compressed as much as necessary and self-ignited at an appropriate time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a valve operation timing control device of a compression ignition type internal combustion engine according to the present invention.

FIG. 2 is a flowchart illustrating a valve operation timing control method according to the first embodiment.

FIG. 3 is a map showing a relationship between an engine speed, an air-fuel ratio of an air-fuel mixture, and a target closing timing of an intake valve.

FIG. 4 is a flowchart illustrating a throttle opening change control method according to the present embodiment.

FIG. 5 is a map showing a relationship between time and correction coefficients α and β.

FIG. 6 is a schematic configuration diagram of another embodiment of the valve operation timing control device for the compression ignition internal combustion engine of the present invention.

[Explanation of symbols]

 4 combustion chamber 7 intake valve 15 VVT 19 air-fuel ratio sensor 20 engine speed sensor

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 41/04 320 F02D 41/04 320 43/00 301 43/00 301K 301Z

Claims (4)

[Claims] 1. A compression-ignition internal combustion engine having an intake valve, wherein the closing timing of the intake valve is advanced in accordance with an increase in the engine speed. Valve timing control device. 2. A valve operation timing control apparatus for a compression ignition internal combustion engine having a combustion chamber and an intake valve, wherein the leaner the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber is, the more the intake valve is operated. A valve operation timing control device for a compression ignition internal combustion engine, wherein a valve closing timing is advanced. 3. A throttle valve and a throttle valve opening changing means for changing an opening of the throttle valve, wherein the throttle valve opening changing means is provided when the change rate of the engine speed is positive. 3. The valve operation timing control apparatus for a compression ignition type internal combustion engine according to claim 1, wherein the opening degree of the throttle valve is increased. 4. A throttle valve and a throttle valve opening changing means for changing an opening of the throttle valve, wherein the throttle valve opening changing means is provided when the rate of change of the engine speed is negative. 3. The valve operating timing control apparatus for a compression ignition type internal combustion engine according to claim 1, wherein the opening degree of the throttle valve is reduced.